> Do those problems exist as much if the excess was forced into them investing into a certain type of power generation?

The premise of "excess" already has the problem baked into it.

Suppose an efficient company could provide service for $100 with a $10 profit, but regulators have no practical way of establishing this. The incumbent is instead providing service for $200 with a $10 profit, but then receiving $30 in kickbacks under the table or something of equivalent value not being accounted for in the official books from whoever is now getting $190 instead of $90.

Whereas getting them to invest in a particular type of generation was never hard because you can just give them a financial incentive to do it. If they have to pay a carbon tax out of their profits, which generation types are they going to add?